The present invention relates generally to welding-type systems and welding-type power sources and, more particularly, to a controller for such systems configured to control a welding-type power source to deliver a variable maximum output according to operating conditions of the welding-type system.
Many welding-type apparatus, for example portable welding-type apparatus, include engine driven generators. In traditional welding generators, the generator is designed to have a rated maximum output that assumes a 100% duty cycle at a given temperature. That is, the engine and generator are designed to operate at the maximum duty cycle at some maximum temperature. As a result, under some operating conditions, the output of the generator may be limited by a maximum operating rating when, in fact, it may not be operating at the maximum duty cycle or the maximum temperature. That is, due to the relationship between operational temperature constraints and high duty cycles, the engine and generator combination is rated at an output that, under nearly all operational conditions, is a worse case scenario and therefore needlessly links output when not operating at those extremes.
Accordingly, the welding-type apparatus incorporating the engine and generator is designed to operate according to the limitations of the engine and generator assuming a 100% duty cycle. Similarly, the welding-type apparatus incorporating the engine and generator is restricted such that under all operational conditions, the engine or generator is not caused to operate above the maximum temperature constraint. Specifically, a maximum rated output is selected such that under a 100% duty cycle in the most stringent operational temperatures, the maximum temperature constraint, or other maximum operational thresholds, is not surpassed.
However, by qualifying such a unit at a maximum rated output of a 100% duty cycle and a stringent operating temperature, the engine and generator, and thereby the welding-type apparatus, are limited from operating above the maximum rated output even when the duty cycle and/or operating temperature are lower than the maximum ratings. That is, under some operating conditions, such as when the duty cycle is less than 100% or the temperature is below the maximum, the engine and generator may be capable of operating above the rated output, but is needlessly restricted.
For example, a given generator may have rated maximum output of 280 Amperes (A) at a 100% duty cycle and at 50 degrees Celsius (C). However, under a lower duty cycle or a lower operational temperature, for example a 50% duty cycle at 30 degrees C., the given generator may be capable of sustaining an output of 325 A. Therefore, while the generator may have a rated maximum output and be configured to operate below that maximum rated output, under some conditions the engine driven generator may actually be capable of an output significantly in excess of the maximum rated output to which it is limited. Accordingly, while under some conditions the engine driven generator may be capable of delivering an output above the maximum rated output, the engine and generator are limited from doing so by the maximum rated output.
It would therefore be desirable to design a welding-type power source incorporating an engine and generator that may be controlled to operate above a maximum rated output dependant as actual operational conditions permit.